What is a PDGS?
The Payload Data Ground Segment (PDGS) is responsible for exploitation of the instrument data. It operationally generates the user products and distributes processed Level-1C and Level-2A products.
Real-time sensed data as well as data played back from on-board saved data are downlinked directly to ground or via the European Data Relay Satellite (EDRS), received, down-converted, demodulated and transferred to the processing facilities for systematic generation and archiving of Level-0 and Level-1/2 data products.
The PDGS includes the facilities responsible for:
- Reception of sensor data and auxiliary data (nrear real time processing);
- Processing of MSI Level-0 to produce Level-1 and Level-2 products applying all the necessary processing algorithms and formatting techniques;
- On demand processing allows requested by external users and hosted inside the PDGS infrastructure;
- Online quality contrrol;
- Production monitoring, including timeliness and completness;
- Rolling Archive;
It interacts with other major components of the ground segment:
- Core Ground Stations - the network of X-band core ground stations located in Alaska, USA, Matera, Italy, Maspalomas, Spain and Svalbard, Norway, are responsible for data acquisition and near real-time processing.
- Processing and Archiving Centres - PACs perform long-term data archiving, data access and systematic non-time critical data processing. Archiving and long-term preservation of data is ensured for all Level-0 data and for a set of configurable systematic higher level products.
- Mission Performance Centres - MPCs are responsible for calibration, validation, quality control and end-to-end system performance assessment. The MPCs include expert teams for specific cal/val, off-line quality control and algorithm correction activities.
- Precise Orbit Determination - POD facilities make use of the GNSS receiver data on-board the SENTINEL satellites to deliver the orbital information needed for generation of mission products.
We are specialists in the design and execution of ground segment payload data processing centers (PDGS):
- Overall system understanding;
- Knowledge of the constraints and operating requirements of processors;
- Knowledge of data formats and associated constraints;
- Cloud and HPC infrastructure, involving our team of specialists infra;
- Optimized processing choregraphy or orchestration;
- Processing cloudification;
- System monitoring;
- Production monitoring with customized KPI.
Our solutions meet the high demands of HPC and cloud execution:
- Implementation of the whole infrastructure with our Infra Team
- Implementation of container-based execution cores with either orchestrators (centralized architecture) or choreography (for resource-saving mass processing)
- Implementation of storage and exchange systems (in particular object storage)
- Implementation of interfaces with PDGS supplier and customer systems
- Definition of processor encapsulation rules: containerization, Docker / Singularity compatibility
- Hardware optimization by targeting the machine type of the project
- Optimization of processor bundles: find the right balance between several processors with regard to the data handled, the location of the data and the hardware required.
- Code optimization: identification of algorithms that can be accelerated, benchmarking, complexity optimization, caching.
- Component optimization: promotion of high-performance open-source libraries.
- Adaptability to cloud/HPC constraints: limited memory execution, calculation time vs. CPU number, controlled disk writing, controlled network access.
- Compliance with maintainability criteria: coding rules, target KPIs under Sonar, UT rate, list of recommended / prohibited technologies, etc.
- Compliance with legal aspects: in particular licences compatible between processors and with the platform.
Our key references
Payload Data & Applications department develops in particular the migration of the Copernicus Sentinel-1 PDGS to the Cloud and the Copernicus Sentinel-2 MPC.